Electron discharge device



2 Sheets-Sheet `1 IIIIIII 4 Nm/55 WasrRAzIo/v ATTORNEY' Elli /5 K L. RONC/ Dec. 8, 1942; v. L RONCI ETAL ELEcTRoN DIscHARGE DEVICE Filed Dec. 28, 1939 Dec. 8, 1942. v. L RoNcl Erm. 2,304,657

ELECTON DISCHARGE DEVICE Filed D60. 28, 1959' 2 Sheets-Sheet 2 .l/.L Ro/vc/ /NVENTO W. asrRATro/v A7' TURA/EV .'trically Welded to its lead-in conductor.

Patented Dec. 8, 1942 ELECTRON DISCHARGE DEVICE Victor L. Ronci, Brooklyn, N. Y., and William D.

Stratton, Paterson, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 28, 1939, Serial No. 311,280

(Cl. Z50-165) 13 Claims.

treated to render the inner surface photoelectris- Y cally sensitive. The anode is supported by the bars of the squirrel cage on circumferential corrugations extending around the inner wall of the container intermediate the two flared ends thereof. One flared end is' conical and serves as the Window through which light is admitted to energize the cathode. The other flared end carries the lead-in Wires for the cathode and anode.

In fabricating or assembling this example of ypractice the inner and outer Walls are formed separately of lime glass. The inner wall comprising the flared end portions and the intermediate corregated portion may be built up of separate sections sealed together, or it may be formed as a unit in a mold With compressed air. The lead-in wires are sealed through the lime glass of the inner wall by means of lead glass beads first fused on the lead-in wires, the lead glass beads being inserted in holes through the lime glass and sealed to the lime glass. anode is formed around the inner Wall and elec- The inner wall is then placed coaxially Within the outer wall and the conically ared end sealed to of silver is slipped to a position such that its en.

tering end is very close to this first seal. With a special set of welding electrodes the cathode lead-in wire is then welded to a short Wire projection previously welded to the cathode. The

small opening is finally closed by sealing the inner and outer Walls together at that point.

Caesium and oxygen are used to sensitize the silver cathode. The caesium is produced by chemical reaction in a side tube during the sensitizing process. The container is connected through The ` incidence.

another side tube to the vacuum pumping station.

The great advantage of this method of fabriy eating the tube is that the glass seals are made at such times and in such ways as not to injure the cathode by excessive heating. The seal between the outer wall and the conically flared portion of the inner wall is made before the cathode is placed in position with an end close to the seal, whereby injury to the cathode by heat employed in the sealing operation is avoided. Due to the are at the opposite end of the inner Wall only a relatively small amount of glass needs to be heated to nally seal this small opening. Thus, the cathode may be made almost as long as the inside of the completed container and' still not be injured during the nal sealing operation. The circumferential corrugations prevent'strains in the glass sufcient to rupture the glass after sealing. The conically shaped window permits light from a small source located on .the axis of the tube and just beyond the end of the tube to enter the window at an advantageousH angle of Other advantages will be. apparent from a consideration of various embodiments of the invention. j y

In a modified example of practicethe 'pellet containing the caesium producing mixture is mounted within the tube container. The pellet is enclosed in a high resistance metallic capsule connected between the ends of a lowresistance open copper ring. This ring carries four springy tungsten wires which in pairs supportvtwo sec-` tions of nickel Wire rings adapted to press against the inner wall near the conical portion when the copper ring and capsule encircle the opposite flared `end of the inner wall, These nickel Wires and connected structure constitute the anode structure. In this modication both the cathode and anode are inserted through the circular opening between the inner and outer Walls after the conically ared end of the inner Wall has been sealed to the outer Wall. y

The invention Will now be described more in detail, having reference to the accompanying drawings. Y

Fig. 1 is a perspective of one embodiment of the invention;

Fig. 2 is a longitudinal section through the axis of the tube of Fig. 1 before the side tubes are sealed off;

Fig. 3 is a cross-section along the line 3-3of Fig. 2 looking toward the terminal end ofthe container under the assumption that the side tubes have been sealed off;

Fig. 4 is a partial longitudinal section of a modified embodiment of the invention;

Fig. 5 is a cross-section along the line 5 5 of Fig. 4 looking toward the terminal end of the container.

The same reference characters are used in the several figures to indicate identical elements.

The embodiment illustrated in Figs. 1, 2 and 3 will rst be described. This embodiment is a photoelectric tube 6 comprising an evacuated glass container I of annular shape mounted on a base 8. The container 1 comprises a cylindrical outer Wall member 9 and a generally cylindrical inner wall member I0. The outer wall member 9 Ais provided with a side tube I I. This tube A-I I is provided for connecting the containerv 'I tothev vacuum pumping station during the sensitizing of the cathode and is later sealed off at vthe constricted portion 36 upon completion of the sensitizing process. The outer wall 9 is also provided'with a side tube I24 within which the reactive mixture lfor producing caesium is placed. This side tube A'I2"is also sealed on" at the constructed portion I3 afterthe cathode has been sensitized. The inner .wallmembernl comprises a'conical Aportion I4y a:f1ared.portion|5 and an intermediate portion II Swhich last portion is provided with two circum ferential vcorrugations I'I extending around the centralportion I 6. yThe lead-in wires for` the cathode and` anode are sealed through the flared portion I5. The lead wires are sealed to lead glass beads whichin turn are sealed to the lime glass 4of the flare.

Thecathode I8 is athin Walled bimetallic tubu- .lanmember of nickel and silver, the inner surface Vbeing of silver of. a higher degree of purity. It is frictionally supported from the outer wallmember ..9-by four spring members I9 which are welded to the convex surface of the cathode I8.

.Theanode 22 is in the general .form of a squirrelcage comprising end rings 23 and connecting bars 24. `Any number of bars may be used. Two

i, aredllustrated. The anodefis made preferably of .nickel and thelbars .24 are bent as shown to press against Athe corrugations I I of the inner wall member' I0.

In assembling this tube it is essential that precautions be takennot to overheat the cathode.

vOverhe'ating would modify the surface structure and-interfere with the sensitizing processlater to be carried out during the vacuum pumping operation.' The structure of this tube and .themethod of, assembling the various vcomponents obviates injury to the cathode and still provides a compact and vefficient structure.

'. The outer Wall member 9 before assembly is in the' form of a hollow lime glass cylinder having vinnerwall member I0 with the anode 22 is inserted into the outer wall member 9 coaxially therewith and the outerend of the conical portion ld'issealed tothe correspondingend of the outer wall member 9 by heating. After this operationjthere remains a small 'circular aperture between the outer` wall member 9 and the flared portion I5.' Enough material to nally seal this aperture is provided in the outer Wall member and the flare, such material being indicated by the dot-dash extensions 25 and 21 in Fig. 2. The cathode I8 is now slipped through this aperture to a position where one end is almost in contact with the sealed junction between the outer wall member 9 and the conical portion I4. The cathode is spaced from the outer wall member 9 by the springs I9 and held in position frictionally thereby. Had the cathode been in this vposition when the seal between the outer wall member 9 and the conical portion I4 was made, it would have been injured by overheating. By

Vthemethod of assembly just described any possible injury is 'obviated The cathode lead-in wire 29 is novi` welded to the intermediate wire 2| by -means of special welding electrodes (not shown) inserted through the small aperture through which the cathode is inserted. The final step of closing the container l consists in sealing the portion 21 of the flaredportion I5 to 'vthe'pon tion'2vof the outer wallmember 9. Comparatively little glass needs to be heated to make this seal so that the cathode I8.may be positioned much closer to this end of the container Ythan as though the portion I5 were not flared.

After the tube hasbeen sensitized .it is mounted on a basev 8 which comprises a cylindrical shell of thermoplastic material secured to the container I atthe terminal end of the container by suitable basing cement 28. yThe cathode lead-in Fig. 2.

VThe caesium Afor sensitizing the cathode is preferablyproduced by chemical -reaction of a mixture in the form of a so-called caesium. pellet. This pellet is mountedin a metallic cup 3l which in turn is connected to a spring.32 by a Wire 33. The spring engages vthe inside Walls of theside tube I2 and holds the metallic cup 3| in position by friction. rEhe caesium pellet is caused to react chemically byinductively heatingthe cup 3I in a well-known manner.

A portion of the cathode I8 opposite the side tube l2 is cut away to permit the caesium to be distilled into thecontainer I and deposit on the inner glass wall thereof rather than to strike the cathode directly.

For simplicity of illustration, the side tubes II and I2 and the lead-in Wire seals 34 and 35 in Figs. 2 and 3 are shown lying in the same plane. Preferably the side tubes are opposite one another as are also the lead-in Wire seals but the seals are angularly offset Vfrom the side tubes bya few degrees, for example, fteen degrees. By such offsetting, the caesium, as it is distilled into the container 7, does not strike directly the anode lead-in wire seal 35.

'A.modied embodiment, of the invention Will now be described by reference to Figs. 4 and 5. This embodiment is ,alsova photoelectric tube 59 comprising an evacuated container 5I of annular shape. The container 5I comprises a cylindrical outer` wall member 52 and a generally cylindricalr inner wall member 53. The outer wall member 52is provided with a side tube 58 shown sealed ou". This tube 58 is provided for 'connecting the container 5l to the vacuum pumping station during the sensitizing of the cathode. The inner wall member 53 'comprises a conical portion 54, a flared portion 55 and an intermediate portion 56, which lastv portion 'is providediwith two circumferential corrugations 51 extending around the central portion 56.

The cathode 59 is a thin walled tubular member similar to cathode I8.j It is frictionally supported from the outerv wall 52 by two' spring members 60 which are welded to the convex surface of the cathode 59. The cathode 59 is also provided with three lead-in wires 62 and 13 which are welded to the cathode and eventually sealed in the glass end wall of the container I.

In this embodiment the caesium pellet is supported within the container 5l. The pellet is contained in a high resistance metallic capsule which is connected between the ends of an open ring 63 of heavy copper wire. The copper wire 63 and capsule 10 together form a closed circuit in which current is electromagnetically induced to heat the capsule and cause chemical reaction of the caesium pellet. Only the capsule 10 is heated to any great extent because the copper wire is of low resistance.

Two pairs of springy tungsten wires 66 and 61 and 68 and 69 are welded to the copper ring 63 in such a way, that the other ends would press against the inner wall member 53 with the ring positioned as in Fig. 4. 'Ihe ends of wires 66 and 61, remote from the copper ring 63, are welded to a section of nickel ring 64 and the corresponding ends of wires 68 and 69 are welded to another similar section ofl nickel ring 65.v The`r sections 64 and 65 are curved so as to conform to the convex surface of the inner Wall member 53 at the place where the intermediate section 56 joins the conical section 54. 'Ihe ends of wires 66, 61, 68 and 69, which are connected to the copper ring 63', are flattened, Wrapped around the copper ring 63 and Welded thereto. Sections 64 and 65 may, for convenience, be called the anode because most of the electrons emitted from the cathode are collected on these elements. These anode members are spring supported from ,the caesium capsule support ring 63 andthe whole assembly may be called the anode struc ture. l i

The process of assembling the tube 50 -is -much like that of tube 6 of Fig. 1. The outer Wall member 52 before assembly is fin the form of a hollow lime glass cylinder having a side tube attached at the position indicated by seal-off tip 58. glass in the form illustrated with the three portions 54, 55 and 56. This inner wall member 53 may be formed in the same manner as the inner wall member I6 of Fig. 1. The inner wall member 53 is inserted into the outer wall memberV 52 coaxially therewith and the outer end of the conical portion 54 is sealed to the corresponding end of the outer wall member by heating. After this operation there remains a small circular aperture between the outer Wall member 52 Aand the flared portion 55. Enough material to 'finally seal this aperture is provided in the' outer wall member 52 and the flared portion 55. The cathode 59 is now slipped through this aperture to a position where one end is'almost in contact with the conical portion 54 of the inner Wall-53.

The inner Wall member 53 is also of lime r 59 by overheating is obviated. The cathode lead-V The cathode is'spaced from the outer wall memjust described,any possible injury to the cathode.

in wire 62 and two support wires 13 protrude through the aperture. The anode structure is next inserted through this circular aperture by springing the anode sections 64 and 65 apart suiciently to pass over the flared portion 55 and the corrugations 51. After the copper support wire 63 reaches the position shown in Fig. 4, the anode'sections (i4y andv 65 spring toward each other and press against the portion 56 of the inner wall member 53 -by reason of the springy tungsten wires 66 to 69, inclusive.A The copper support Wire 63 is provided with a lead-in wire 12: and three additional support Wires 14. These lead-in and support wires` are connected to the copper ring 63 through short sections of nickel wire 16 which, in turn, are wrapped. around and welded to the copper ring 63. 'I'hese lead-in and support Wires also protrude through the aperture' after the anode structure had been inserted in its properposition. The final step of closing the container 5| consists in sealing the ared portion 55 to the outer wall member 52. During this sealing operation the lead-in wires and support wires which protrude through the aperture, are also sealedto the glass to form vacuum tight seals. The support wires y13 and 14 may be cut off flush with the glass seal, while the lead-in wires 12 and 62 are later connected to the tube base terminals.

`It is to vbe noted that the cathode in the modified embodiment illustrated in Fig. 4 does not extend as close to the finally sealed portion of the container 5l as in the embodiment illustrated in Fig. 2. The caesium capsule, however, inl the embodimentillustrated in Fig. 4, is comparatively close to such seal and can be so placed without overheating and prematurely flashing the'caesium pellet because comparatively little glass needs to be heated to make this seal and the over-all dimensions of container 5I can be made smaller than as though the portion 55 were notiiared.

The .cathode 59 is provided with a slit 6I to obviate injurious eddy currents in the cathode due to the magnetic eld from the energizing magnet (not shown) positioned to induce heating current in the capsule 10. The form of the capsule may be the same as that disclosed in C. H. Prescott, Jr., Patent 2,097,467 patented November 2,V 1937. It may be secured to the ends of the copper ring 63 by inserting the end tabs of the capsule in slits in the ends of the copper ring 63 or by clamping in the manner illustrated inthe Prescott patent supra. The use of slits in the ends of the copper ring 63 is preferred because of space conditions.`

In order to prevent the hot caesium vapor produced by the chemical reaction of the caesium Vby means of support wire 15 welded at one end to the shield 1I and at the other end to the copper wire 63.

This completed tubemay also be mounted on a base like that shown in Fig. 1.

The cathode may be sensitized in any wellkno'wn manner after the tube structure has been fabricated. A'preferred lmethod is very similar to that described in Patent No. 2,178,227 of M. S. Glass patented October 31, 1939. The method therein described is modified .to'take into account the diierence in sizes of thercathodes and, in the case of the embodiment of Figs. 1, 2 and 3 the fact thatthe caesiumis produced in a side tube and'must be driven into the tube container by heating or flaming theside tube.

Briefly described, the preferred method of sensitizing the cathode is as follows:

The tube is baked at about 400 C. to remove occluded gases from the bulb but this heating does not cause any chemical reaction in the caesium pellet. Oxygen is admitted into the container and the cathode is subjected to ionic bombardment in suchy a way that the first effect is to produce a heavy layer of silver oxide on the inner surfacey of the tubular cathode followed by a heating up of the silver tube and reduction of the layer of silver oxide. This cycle of oxidation and reduction is repeated after which the oxygen is pumped' out of the container. This treatment leaves the inside surface of the cathode clean and slightly roughso that it has a uniform matte iinish. A fresh charge of oxygen is admitted and by a succession of'discharges of fixed amounts of electricity from condensers, the inner surface of the cathode is oxidized to an amount dependent upon the amount of caesium to be introduced. The caesium pellet is then inductively heated to effect a chemical reaction which produces caesiumyapor. This vapor condenses on the inside Walls of the side tube in Fig. 2 and on the inside Walls of the container `in Fig. 4. By heating the side tube in Fig. 2 `with a flame the caesium is driven into and condenses principally on the inside Walls of the container. The tube is then heated in a stream of hot air to a temperature of about 225 C. until the cathode has reached the desired sensitivity. Argon or other suitable gases maybe admitted at low pressure to obtain the benetsof gas amplification.

Other materials may be used for the cathode and modied treating methods may be employed. Some of these materials and modified methods are described in the Glass patentsupra. The ingredients of the caesium pellet are preferably those disclosed in this Glass patent.

While the examples of practice illustrated herein arev photoelectric tubes, certain features of the invention are applicable to electron discharge devices generally. The feature of sealing the inner and outer Walls together at such times as not to injure the cathode by overheating is applicable to vany type of cathode which is injured by the temperatures necessary to seal the inner and outer Walls together. Such cathodes may be therrnionic, photoelectric, secondary emitting, or so-called -cold cathodes, such as are used in gaseous discharge devices. The material of the cathode may be other-than silver. Furthermore, the end of the outer Wall member may be compressed to form a-small circular aperture With an unflared inner Wall member, inwhich case the outer electrode is preferably of a form which expands after it is inserted through. the circular aperture. Still other embodiments of the invention will occur to those skilled in the electron discharge art in view of the specific examples herein disclosed.

What is claimed is:

l. An electron discharge device comprising an annular container having an outer cylindrical Wall and an inner cylindricalwall having a conical portion forming a Window' at: one end, said Walls being sealed together at the respective ends of said walls, a 'tubular cathode within said'container coaxial with' said walls and supported from said outer Wall but separated therefrom, an anode within said container and also inside saidl cathode, and lead-in wires sealed through said container wall and connected to said cathode and anode, respectively.

2. A method of manufacturing an electron discharge tube havingv an annular shaped container the outer Wallv element of which is substantially cylindrical, and having an electrode member shaped toconform approximately to said outer wall element, which member may be injured by heat, which method comprises forming for the inner wall of said container an element of generally cylindrical shape having one end flared to a diameter slightly less than the diameter of said outer cylindrical Wall element, positioning said Wall elements concentrically with the ends of one adjacent the .respective ends of the other, sealing said elements together at the end remote from said flared portion by the application of heat, inserting said electrode member into said container through the space between said outer wall element and the outer end of said Ilared portion and securing it in position in said container so that it extends so close to the end thereof which has been sealed that it Would have been injured by the heat applied in sealing had it then been so positioned, and subsequently sealing together said wall elements at the other end of said container.

3. A method of manufacturing in electron discharge device having an annular shaped container the Walls of which are generally of cylindrical shape for at least a large portion of their length, and having a cathode member of approximately cylindrical shape, said member may be subject'to injury by heat, which method comprises forming said lWalls separately and providing a taper at one end of at least one of said walls so that when said walls are assembled with their ends aligned the tapered extremity is slightlyv spaced from the adjacent end of the other Wall, assembling said Wallsl so that this spacing is effected, sealing together the other ends of the Walls, inserting the cathode into the container through said space, and then applying heat to the wall ends which are spaced apart to eiTect softening and sealing.

4. A photoelectric tube comprising an outer cylindrical Wall, an inner cylindrical Wall having a conical portion at one end sealed to said outer Wall and the other end also sealed to said outer Wall, a tubular light sensitive cathode supported Within said container and surrounding the major portion of said conical portion of said inner wall, an anode also supported Within said container and lead-in Wires sealed through said container Wall and connected to said cathode and anode, respectively.

5. A photoelectric tube comprising an outer cylindrical Wall, an inner cylindrical Wall sealed at one end to said outer wall and having the other-end also sealed to said outer wall and a central` circumferentially corrugated portion, a tubular light sensitive cathode supported Within saidcontainer surroundingsaid corrugated portion of said inner wall, an anode also supported Within said container, and lead-in Wires sealed through said container Wall and connected to said cathode and anode, respectively.

6. A photoelectric tubey comprising an outer cylindrical Wall, an inner cylindrical Wall having one end Sealed to said outer wall anda flared portion at the other end also sealed to. said outer Wall, a tubular light sensitive cathode within said container surrounding the inner wall near the end opposite the flared portion, a metallic capsule for light sensitive material connected between the ends of an open low resistance metallic ring, said ring lfor-ming part of the anode for said tube, and lead-in wires sealed through said container wall and connected to said cathode and anode, respectively.

7. An electron discharge device comprising an annular container having an outer cylindrical Wall and an inner cylindrical wall having a central circumferentially corrugated lportion, said walls being sealed together at the respective ends of said Walls, a cathode conforming generally to n the inside surface of said outer wall but separated therefrom -positioned within said container and frictionally supported from said outer wall, an anode within said container, and leadin wires sealed through said container Wall and -connected to said cathode and anode, respectively.

8. An electron discharge device comprising an annular container having an outer cylindrical Wall and an inner cylindrical wall having a conical portion at one end, means closing the space between the respective ends of said walls with the inner wall within and coaxial with the outer wall, a tubular cathode within said container, means supporting said cathode from said outer wall in a position separated from said outer wall at a plurality of separated frictional points of relatively small area compared with the area of the cathode and surrounding the major portion of said conical portion of said inner Wall.

9. An electron discharge device comprising an annular container having an outer cylindrical wall and an inner cylindrical wall coaxial with said outer Wall and having a central circumferentially corrugated portion, a tubular cathode spring supported from said outer Wall, an anode supported in operative relationship to said cathode, and lead-in Wires connected to said cathode and anode, respectively.

10. A method of manufacturing an electron discharge device having an annular-shaped container the outer wall element of which is substantially cylindrical, and a tubular cathode which is injured by excessive heating, which method comprises forming for the inner wall an element of generally cylindrical shape having one end flared to a diameter slightly smaller than the diameter of the outer wall element, positioning the inner wall element within and coaxial with said outer Wall element leaving a small opening between the outer Wall and said ared portion of said inner wall, sealing the end of the inner wall element opposite said flared portion to the outer wall element, inserting the tubular cathode into said container through said opening, supporting an anode Within said container during assembly, and sealing the inner and outer wall elements together adjacent said opening closing said opening.

11. A photoelectric tube comprising an outer cylindrical wall, an inner cylindrical wall having a conical portion at one end sealed to said outer wall, a ared portion at the other end also sealed to said outer wall and a central circumferential corrugated portion, a tubular light sensitive cathode supported within said container and surrounding the major portion of said conical portion of said inner Wall, an anode also supported within said container, and lead-in wires sealed through said container wall and connected to said cathode and anode, respectively.

12. A photoelectric tube comprising an outer cylindrical wall, an inner cylindrical Wall having a conical portion at one end sealed to said outer Wall, a iiared portion at the other end also sealed to said outer wall and a central circumferential corrugated portion, a tubular light sensitive cathode supported Within said container and surrounding the major portion of said conical portion of said outer wall, an anode spring supported on said corrugations within said container, and lead-in wires sealed through said container wall and connected to said cathode and anode, respectively.

13. A photoelectric tube comprising an outer cylindrical wall, an inner cylindrical wall having a conical portion at one end sealed to said outer wall, a ared portion at the other end also sealed to said outer wall and a central circumferential corrugated portion, a tubular light sensitive cathode spring supported from the outer wall within said container, an anode also supported within said container, and lead-in wires sealed through said container wall and connected to said cathode and anode, respectively.

VICTOR L. RONCI. WILLIAM D. STRA'I'ION. 

